Barberry is considered a mildly toxic plant for humans, causing digestive upset if plant parts are consumed and dermatitis reactions if the plant is handled. While it is not included on official lists of plants toxic to pets, this may be because the thorny stems make consumption very unlikely. The berberine contained by the plant parts is known to cause cardiac symptoms if consumed in large quantity, so it is wise to not grow this plant if you have pets prone to chewing on painfully thorny stems.
Light
Japanese barberry grows best in full sun. But it can tolerate some shade, especially at the warmer end of its growing zones. Around seven hours of sunlight per day is ideal for bright, lush foliage.
Soil
This shrub readily grows in average soil. It can tolerate a range of soil conditions, as long as there is good drainage. Soggy soil can cause root rot.
Water
Japanese barberry has good drought tolerance, so you’ll likely only need to water your shrub during prolonged dry periods. If the plant’s leaves are wilting or falling off during the growing season, that’s a common sign it could use some water. Moreover, give a new shrub regular watering to maintain slight moisture in the soil during its first growing season.
Temperature and Humidity
Japanese barberry can adapt to many climate conditions and does well throughout USDA growing zones 4 to 8. It has good cold tolerance but prefers to be sheltered from strong winds. It can struggle in very hot and humid conditions.
Fertilizer
Fertilizing Japanese barberry is generally not necessary unless you have very poor soil. To boost plant health and vigor, you can fertilize your barberry in the late winter or early spring before flowering begins with a slow-release shrub fertilizer.
Types of Japanese Barberry
There are several cultivars of Japanese barberry that vary in size, shape, and appearance. Some have an upright and rounded growth habit while others tend to spread out or remain rather small. Plus, some shrubs feature striking foliage colors besides the typical green. Popular varieties include:
‘Crimson Pygmy’: True to its name on both counts, this variety bears reddish-purple foliage and remains compact. It usually reaches around 2 to 3 feet tall and wide.‘Aurea’: This plant also remains rather short, topping out at 3 to 4 feet tall and slightly wider. It is known for its vibrant yellow foliage.‘Rose Glow’: This variety reaches around 5 feet tall and 4 feet wide. Its claim to fame is the fact that its leaves have three colors: a rosy red that’s mottled with pink and white.‘Concorde’: This compact, rounded shrub only reaches around 2 feet tall and wide. It features deep purple foliage that becomes even more vivid in the fall.
Pruning
Pruning generally isn’t essential for Japanese barberry shrubs. If you wish, you can leave them alone and only prune off dead, damaged, or diseased portions as needed. Or you can prune to obtain a specific shape or size, such as pruning to create a hedge. This more extensive pruning should take place immediately after the shrub flowers in the spring or the early summer. Avoid pruning within two months of your projected first frost date in the fall (unless you’re removing damaged portions), as this can leave the shrub vulnerable to injury or disease. Whenever you’re working with a Japanese barberry shrub, wear gloves to protect yourself from the plant’s extremely sharp thorns and the skin reactions caused by contact with the plant.
Propagating Japanese Barberry
It’s easy to propagate Japanese barberry with cuttings, the preferred method over the more challenging way of growing from seeds. Take cuttings in the spring after flowers have faded. You can also take semi-hardwood cuttings in the summer. Here’s how:
How to Grow Japanese Barberry From Seed
Consider that Japanese barberry self-seeds so freely, it’s no surprise that propagating plants from seeds is an easy matter. The tiny red berries contain small seeds that can be planted in almost any growing medium. Collecting a few berries in fall and planting the seeds in pots filled with ordinary potting mix will generally produce new plants. Small plants that self-seed in the garden can also be easily dug up and transplanted into new locations.
Overwintering
Japanese barberry requires no special winter protection within its hardiness range.
Common Pests & Plant Diseases
Japanese barberry shrubs are susceptible to scale insects and aphids, which will suck on the plant’s juices. Dislodge large infestations of aphids with a high-pressure garden hose spray. Diseases that can afflict the plant include powdery mildew, verticillium wilt, anthracnose, and bacterial leaf spots. Use fungicides for most problems, but note that wilt may be irreversible and cause the shrub to die.
How to Get Japanese Barberry to Bloom
The small yellow flowers of the Japanese barberry are not particularly showy, but they may be desirable as the prerequisite for the winter appeal of the bright red berries that follow. When a shrub fails to bloom, it is usually because it is not receiving enough direct sunlight, or because it is being over-fertilized. Severe pruning too early in the growing season can also temporarily halt flower production. When pruning is necessary, it’s best to do it after the season’s flowers have faded, or well before new spring growth begins.
